Android phones can implement multiple user profiles at OS level, and these can at least provide security against cursory visual inspection.

Ideally you'd use credential derived encryption for each user's storage area on the device, and avoid leaking the number of profiles on the device. The UX for that is "hard" - even a single login screen that (with a naive implementation) accepts 1 of N PINs would be vulnerable to a timing attack as the PIN is tested against each "profile".

There's a few gotchas around carrier services like SMS and voice calls (do these go only to the main user account?), but maybe in future you could see an eSIM per profile... Doesn't protect you against a colluding mobile operator though - ultimately it all comes down to your threat model.

Not even dual boot. Just depending on the password/pattern entered, log in as a different user. It's possible to do in Android as an app. I've been meaning to write one, but it seems like lots of work and upkeep.

What you describe might be almost achievable using Android work mode, and an open source tool like Island - you can have a second instance of apps (like WhatsApp or signal or telegram) independent of the first instance, and you can turn work mode off if needed.

If your adversary knows about work mode though and checks if it's available, this won't help you much.

VeraCrypt has that:

https://veracrypt.fr/en/Plausible%20Deniability.html

That would be possible if our phones wouldn't be all locked up by the manufactures and instead we could install the OS we wanted... One can dream

I've been daily driving the Pinephone Pro and other then super sort battery life because no support for suspend yet (~3 hours) its been great! Actually usable and quite a bit of fun. Not recommended to anyone who's not fully confortable installing their own linux distros and using workarounds, though. The future you dream of is coming!

I really hope so! I might get one of those to start playing a bit.

There is also Librem 5 as an alternative.

If you can get one! I preordered in 2018 and haven't gotten mine yet, while for approximately the same amount of money and less time I have also ordered, received, and used 3 different Pinephone editions.

See here about delivery progress: https://forums.puri.sm/t/estimate-your-librem-5-shipping/112.... Every time Purism can get the CPUs, they deliver another bunch of the phones. (I'm also waiting for my phone).

Apps that may have sensitive information could have a dual-mode: if you open the app, you only see your "public" content, and if you do some gesture that you configured (like drawing some shape on the screen but without a "lock screen"), you see the full contents.

nice!

Doubtful it will ever come as a standard. Mainstream operating systems are developed in US and things aren't that bad there. And when they start to become that bad there will be legislation to prevent such features.

Web based services? Only use incognito mode? (Firefox on mobile can be configured to use Private mode by default)

Androids support multiple users and encrypted storage. Or you can reset your phone and restore it from cloud storage. Or use your second finger for biometric unlock, and lock up the phone on failing with your index finger.